window.onscroll = function(){
var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
var waterflow = Node.one(".zebra-yao-waterflow");
if(scrollTop >= waterflow.offset().top) {
if(!Node.one(".yao-waterflow-tab").hasClass("position-fixed")) {
Node.one(".yao-waterflow-tab").addClass("position-fixed");
}
} else {
if(Node.one(".yao-waterflow-tab").hasClass("position-fixed")) {
Node.one(".yao-waterflow-tab").removeClass("position-fixed");
}
}
}
.position-fixed {
position: fixed;
top: 0px;
left: 0px;
}